首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   21383篇
  免费   1369篇
  国内免费   291篇
耳鼻咽喉   42篇
儿科学   524篇
妇产科学   204篇
基础医学   3653篇
口腔科学   369篇
临床医学   2108篇
内科学   1711篇
皮肤病学   149篇
神经病学   3967篇
特种医学   215篇
外国民族医学   1篇
外科学   551篇
综合类   1877篇
一般理论   1篇
预防医学   4720篇
眼科学   41篇
药学   2325篇
  9篇
中国医学   231篇
肿瘤学   345篇
  2024年   76篇
  2023年   337篇
  2022年   716篇
  2021年   996篇
  2020年   756篇
  2019年   627篇
  2018年   598篇
  2017年   666篇
  2016年   712篇
  2015年   682篇
  2014年   1219篇
  2013年   1645篇
  2012年   1064篇
  2011年   1211篇
  2010年   879篇
  2009年   924篇
  2008年   953篇
  2007年   919篇
  2006年   853篇
  2005年   688篇
  2004年   546篇
  2003年   522篇
  2002年   466篇
  2001年   355篇
  2000年   283篇
  1999年   269篇
  1998年   221篇
  1997年   205篇
  1996年   173篇
  1995年   162篇
  1994年   148篇
  1993年   128篇
  1992年   139篇
  1991年   133篇
  1990年   119篇
  1989年   119篇
  1988年   121篇
  1987年   100篇
  1986年   148篇
  1985年   250篇
  1984年   242篇
  1983年   175篇
  1982年   214篇
  1981年   202篇
  1980年   198篇
  1979年   185篇
  1978年   129篇
  1977年   141篇
  1976年   130篇
  1975年   93篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
Sham-operated male doves displayed greater nesting activity under long days (16L:8D) than under short days (8L:16D). This difference was abolished by pinealectomy—the activity of long-day pinealectomized birds dropped to a level comparable to that seen on short days. Removal of the pineal had no effect under the short photoperiod. These results are not due to changes in peripheral androgen production as castrated, testosterone-implanted males also exhibited higher levels of nest-building on long days if sham-operated, but not if they were pinealectomized. Neither treatment had a significant effect on courtship or copulatory behavior. It is suggested that the pineal mediates the stimulatory effect of long photoperiods on hormonally-induced nest-building in doves.  相似文献   
142.
Hungry rats display the characteristic "satiety sequence" after drinking a glucose solution: The end of ingestion is accompanied by grooming and exploring, followed by resting. With saccharin solutions over a range of concentrations, however, ingestion is accompanied and followed by persistent grooming and exploring; resting rarely occurs. Gastric preloads of glucose solution promote resting to reinstate the "satiety sequence" after a bout of saccharin ingestion. Therefore, the systemic effects of glucose are sufficient to promote resting. In the absence of postingestive factors, the "satiety sequence" is incomplete following saccharin ingestion as it is after sham-feeding.  相似文献   
143.
Rats equipped with tubes leading to their stomach, duodenum or jejunum were infused with a liquid diet for 9 hr (4 ml/hr) and were allowed to eat during the last 8 hr of infusion. All rats ate significantly less on diet infusion days than on saline or no infusion days. A second study showed that a taste aversion could not be conditioned to flavored water associated with diet infusion. Apparently, intrajejunal injection of nutrients produces satiety and not discomfort. Infusion of the diet for 5 consecutive days into the stomach, duodenum or jejunum consistently and significantly lowered food intake by reducing meal size, not meal frequency. Results suggest that the small intestine below the infusion site contributes to normal satiety.  相似文献   
144.
A monitoring system to continuously record the daily pattern of drinking and eating of rats is described. This system, based on a North Star microcomputer, can record the amount of food ingested with a temporal resolution of +/- 1.0 second and quantitative accuracy within +/- 5%. Drinking behavior is detected using a drinkometer which also has a temporal resolution of +/- 1.0 second. Data are analyzed by computer to determine absolute amounts of consumption and patterns of intake. The patterns of feeding and drinking recorded by this system are similar to those observed using other monitoring devices.  相似文献   
145.
Using an FT 60 schedule, rats on 100% free feeding tested in the dark phase of a 12:12 light-dark cycle were trained to self-administer ethanol intravenously. The effect was dose-dependent with 20% ethanol being the preferred dose as measured by the number of infusions. Daily administration of 1.5 mg/kg melatonin significantly increased ethanol self-injection in the dark but not in the light. The time of day of testing and/or drug administration may be an important variable in studies on self-administration of drugs. Testing in the dark may eliminate the need for reducing body weight when inducing self-administration of ethanol.  相似文献   
146.
幼儿攻击性行为游戏矫正的倒返设计研究   总被引:2,自引:0,他引:2  
目的:探讨幼儿集体游戏用于矫正幼儿攻击性行为的效果。方法:采用倒返实验,对三名被试进行了游戏矫正。结果:三名被试在实验的基线阶段有明显的攻击性行为,游戏介入后攻击性行为明显减少,游戏取消后攻击性行为再度增加,游戏再次介入后,攻击性行为再次明显减少;方差检验的结果表明,被试在基线阶段的攻击性行为与游戏矫正后的攻击性行为差异极显著。结论:运用自然的幼儿集体游戏可以矫正幼儿的攻击性行为。  相似文献   
147.
The effects of blockade of D1 and D2 dopamine receptors in the nucleus accumbens on changes in glutamate levels in the intercellular space of this structure during food consumption were studied in Sprague–Dawley rats by intracerebral microdialysis combined with HPLC. These experiments showed that food consumption was accompanied by decreases in glutamate levels in the intercellular spaces of the nucleus accumbens. Blockade of D1 dopamine receptors with SCH-23390 (0.01 mM) produced no changes in the dynamics of glutamate release during food consumption. Food consumption in conditions of blockade of D2 dopamine receptors with raclopride (0.01 mM) induced increases in glutamate levels. These data suggest that glutamate levels during food consumption are controlled by the dopaminergic system of the nucleus accumbens, mediated by D2 but not D1 dopamine receptors.  相似文献   
148.
We have studied three children with de novo terminal deletion of the long arm of chromosome 1 (46,XX,del(1)(q43)). They all have minor anomalies and neurological signs (severe psychomotor developmental delay, generalized hypotonia, and seizures) that have been described previously. In addition, all of these three patients have autistic-like behavior. They avoid eye contact, show no interest in people, express little emotion, and repeat stereotypic movements such as head nodding and purposeless finger manipulation. They also spend excessive time in making unusual sounds consisting of a high-pitched shrill cry with little intonation in infancy and a harsh, strained, and glottal stridency in later life. They make no labial, lingual, or nasal sounds. We suggest that these observations may be unique clinical manifestations of certain terminal 1q deletions.  相似文献   
149.
Vagal mediation of the cholecystokinin satiety effect in rats   总被引:2,自引:0,他引:2  
Central (intracerebroventricular) and peripheral (intraperitoneal) injections of the octapeptide of cholecystokinin (CCK-8) were compared to determine the most effective route of administration to elicit satiety for food intake in the rat. Subdiaphragmatic bilateral vagotomy and spinal cordotomy (T2-T3) were also performed to investigate the importance of visceral nerves for the satiety effect. CCK-8 suppressed feeding and elicited satiety resting behavior when injected peripherally but it was less effective when injected centrally. The satiety effect of CCK-8 or CCK-33 following peripheral injections was blocked by vagotomy whereas spinal cordotomy had no effect. The results indicate that some component of the vagus is required to mediate the peripherally induced cholecystokinin satiety effect, but the splanchnic nerves are not necessary. The weak effect of CCK-8 following ventricular administration is additional evidence suggesting that cholecystokinin of intestinal origin acts in the periphery rather than directly on the brain to elicit its typically rapid satiety effect in rats.  相似文献   
150.
行为问题儿童的生活质量及其影响因素调查   总被引:18,自引:0,他引:18  
目的:探讨行为问题儿童的生活质量及影响因素.方法:采用Conners量表和儿少主观生活质量问卷调查2087例少年儿童的行为问题和生活质量,然后将问题儿童与正常儿童的结果做比较.结果:行为问题儿童的生活质量明显低于正常儿童,相关分析显示儿少主观生活质量问卷与Conners量表父母问卷和教师评定量表的部分因子存在不同程度的相关.逐步回归显示儿童的学业、行为问题、家庭经济、父亲性格、年龄、父母对不良行为的处理方式、独生共7个变量影响着儿童的生活质量.结论:行为问题儿童生活质量下降,需要得到学校、家庭、同伴、社会等多方面的关怀帮助.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号